Organic acids and oligomers thereof have been shown to promote plant growth. Typical promoters of plant growth are described by Kinnersley et al., Plant Growth Regulation, 9, pp. 137-146 (1990) (lactic acid and relatively low molecular weight oligomers of lactic acid); in U.S. Pat. No. 4,813,997 to Kinnersley et al. (oligomers of glycolic and/or L-lactic acid) and in U.S. Pat. No. 4,799,953 to Danzig et al. (oligomers of thiolactic and thioglycolic acids). All of the forgoing approaches to plant growth promotion appear to focus on coordination as a means for increasing plant uptake of compounds vital to the growth of the plant, e.g., micronutrients such as calcium, magnesium, sulfur, manganese, zinc, copper, iron, boron, and the like.
A common approach to promoting plant growth has been, and continues to be, the use of nutrients (fertilizers), natural as well as synthetic. Synthetic nutrients usually provide nitrogen in a plant-usable form, such as urea for example, and/or inorganic nitrates, phosphates, or the like compounds. While such nutrients may be applied, more or less, at the convenience of the farmer, and may be applied as often as deemed desirable, the overuse of synthetic nutrients and the inefficient use of synthetic nutrients are major factors responsible for environmental problems such as eutrophication of groundwater, nitrate pollution, phosphate pollution, and the like. An overview of the undesirable effects of nitrogen fertilizer is presented by Byrnes, Fertilizer Research, 26, pp. 209-215 (1990).
To ameliorate the problems attendant to inefficient nutrient use and nutrient overuse, there is an ongoing desire and need for environmental and production reasons to increase fertilizer efficiency and enhance plant productivity. There is a need, therefore, to maximize the availability, uptake and utilization of plant nutrients while minimizing loss of nutrients or fertilizer elements through leaching, denitrification, vaporization and other mechanisms that prevent assimilation of these nutrients by the biological and physical mechanisms of plants.
The present invention addresses and resolves these problems by methods and compositions which provide a favorable environment for enhancing the utilization of nutrients by germinating or growing plants resulting in enhanced plant productivity.